The asymmetric unit of the title compound, C14H24N2O5S, contains two independent molecules (A and B). In each molecule, the isothiazolidin-3-one ring adopts an envelope conformation with the methylene C atom as the flap. In the crystal, the A molecules are linked to one another by N—H...O hydrogen bonds, forming columns along . The B molecules are also linked to one another by N—H...O hydrogen bonds, forming columns along the same direction, i.e. . Within the individual columns, there are also C—H...S and C—H...O hydrogen bonds present. The columns of A and B molecules are linked by C—H...O hydrogen bonds, forming sheets parallel to (10-1). The absolute structure was determined by resonant scattering [Flack parameter = 0.00 (3)].